Polyester resin having improved processability

Abstract

A polyester resin is disclosed which is resistant to splitting during transverse orientation during conventional film manufacturing. The polyester resin contains up to 7 weight percent, based uon the total weight of the resin, of (A) a dicarboxylic acid component consisting essentially of 1,4-cyclohexandeicarboxylic acid having a trans isomer content of at least 70% (B) a glycol component consisting essentially of (1) 1,4-cyclohexanedimethanol, and (2) from about 15 to about 50 weight percent, based on the weight of the polyesterether, of polytetramethyleneether glycol having a molecular weight of about 500 to about 1100 and (c) from about 0.1 to about 1.5 mole percent, based on the mole percentage of the acid or glycol component, of a branching agent having at least three COOH or OH functional groups and from 3 to 60 carbon atoms.

I claim: 
     
       1. A polyester resin containing a copolyesterether comprising: (A) a dicarboxylic acid component consisting essentially of 1,4-cyclohexanedicarboxylic acid having a trans isomer content of at least 70%,   (B) a glycol component consisting essentially of (1) 1,4-cyclohexanedimethanol, and   (2) from about 15 to about 5weight percent, based on the weight of the polyesterether, of polytetramethyleneether glycol having a molecular weight of about 500 to about 1100 and     (C) from about 0.1 to about 1.5 mole percent, based on the mole percentage of the acid or glycol component, of a branching agent having at least three carboxyl or hydroxyl functional groups and from 3 to 60 carbon atoms, said copolyesterether being present in said polyester resin in an amount effective to reduce the occurrence of film splitting during the production of biaxially oriented film from said resin but not exceeding 7 weight percent, based upon the total weight of the polyester resin and the copolyesterether.     
     
     
       2. The resin of claim 1 wherein the 1,4-cyclohexanedicarboxylic acid has a trans isomer content of at least 80% and the 1,4-cyclohexanedimethanol has a trans isomer content of at least 60%. 
     
     
       3. The resin of claim 1 wherein the 1,4-cyclohexanedicarboxylic acid has a trans isomer content of at least 85% and the 1,4-cyclohexanedimethanol has a trans isomer content of at least 60%. 
     
     
       4. The resin of claim 1 wherein the molecular weight of the polytetramethylene ether glycol is from about 500 to 1000. 
     
     
       5. The resin of claim 1 wherein the polytetramethylene ether glycol is present in an amount of from about 20 to 35% based on the total weight of the copolyesterether. 
     
     
       6. The resin of claim 1 wherein the branching agent is trimellitic anhydride. 
     
     
       7. The resin of claim 1 further comprising an antioxidant ranging from 0.1 to 1.0 percent by weight, based upon the weight of the copolyesterether. 
     
     
       8. The resin of claim 1 wherein the die swell of said copolyesterether is between about -50% and +50%. 
     
     
       9. The resin of claim 1 wherein the minimum crystallization time of said copolyesterether is less than one minute. 
     
     
       10. The resin of claim 1 wherein the minimum crystallization time of said copolyesterether is less than one-half minute. 
     
     
       11. The resin of claim 1 having from 2.50 to 5.0 weight percent of said copolyesterether. 
     
     
       12. A polyester resin having from 2.5 to 5.0 weight percent, based upon the total weight of the resin, of a copolyesterether comprising (A) a dicarboxylic acid component consisting essentially of 1,4-cyclohexanedicarboxylic acid having a trans isomer content of at least 80%,   (B) a glycol component consisting essentially of (1) 1,4-cyclohexanedimethanol having a trans isomer content of at least 60%, and   (2) from about 20 to about 35 weight percent, based on the weight of the polyesterether, of polytetramethyleneether glycol having a molecular weight of about 500 to about 1000 and     (C) from about 0.1 to about 1.5 mole %, based on the mole % of the acid or glycol component, of a branching agent having at least three carboxyl or hydroxyl functional groups and from 3 to 60 carbon atoms.   
     
     
       13. The resin of claim 12 further comprising from 0.01 to 3.0 weight percent based upon the total weight of the resin, of inert particles selected from the group of silica, barium sulfate, hydrated alumina, and calcium carbonate. 
     
     
       14. The resin of claim 13 wherein said particles have an average particle size in the range of from 0.2 to 30 microns. 
     
     
       15. The resin of claim 13 wherein said particles possess a bimodal particle size distribution. 
     
     
       16. The resin of claim 15 having from about 0.3 to about 2.5 percent by weight of a small particle size inert additive having an average particle size of from 10 to 1,000 millimicrons and a large particle size inert additive having an average particle size of from 0.5 to 30 microns, said large particle size inert additive being present in a concentration ranging from 0.002 to 0.015 percent by weight of said resin. 
     
     
       17. A biaxially-oriented polyester film prepared from the resin of claim 1. 
     
     
       18. A biaxially-oriented polyester film prepared from the resin of claim 12. 
     
     
       19. A coextruded polyester film in which at least one layer comprises the polyester film of claim 12.